1. Field of the Invention
The present invention relates to methods, apparatus and products for filtering. In another aspect, the present invention relates to methods, apparatus and products for filtering streams of gas and/or liquids to remove solids and/or entrained liquids. In even another aspect, the present invention relates to methods, apparatus and products for filtering, utilizing a filter system in which that portion of the filter system more likely to accumulate filtrate is replaceable apart from that portion of the filter system which is less likely to accumulate filtrate. In even another aspect, the present invention relates to methods, apparatus and products for filtering, utilizing a two stage filter system in which that portion of the filter system in the first stage is more likely to accumulate filtrate is replaceable apart from that portion of the filter system in the second stage which is less likely to accumulate filtrate.
2. Brief Description of the Related Art
There are a number of applications in which it is necessary to remove solids or liquids from a gas stream, liquid stream, or multi-phase stream. As a non-limiting example, solid or liquid contaminants may be present in various gas or liquid streams of a refrigeration system. As another non-limiting example, gas pipelines many times contain solid or liquid contaminants.
Various apparatus and methods for removing solids and/or liquids from gas streams are well known. Quite commonly, gas filter elements are utilized for filtering dry gas streams as well as for separating solids and liquids from contaminated gas streams, or for coalescing entrained liquids from a gas stream. Often these types of gas filter elements are installed in multi-stage vessels, which are in turn installed in a gas pipeline, to perform these filtering functions.
There are a number of patents that relate to removing solids and/or liquids from gas streams, the follow of which are merely a small sampling.
U.S. Pat. No. 6,381,983, issued May 7, 2002, to Angelo et al., discloses an improved filter drier for a refrigeration system having a replaceable tubular filter element. A desiccant assembly is removably secured within a housing. The assembly includes a first and second molded desiccant, a hollow tubular perforated core located within said first and second molded desiccant, and a tubular filter located over said core.
U.S. Pat. No. 6,692,639, issued Feb. 17, 2004, to Spearman et al., discloses a conically shaped filtration and/or separation apparatus that is constructed from a stack of filters at least some of which are different sizes superposed above each, other, of said plurality of said filters in a fluid communicable relationship. A collapsible version of such conically shaped filter and/or separation apparatus is provided whereby a plurality of such filters are connected together using two piece interlocking or connecting end caps.
U.S. Pat. No. 6,858,067, issued Feb. 22, 2005, to Burns et al., discloses a filtration vessel for use with a rotary screw compressor that receives a compressed liquid/gas mixture from the compressor. The vessel utilizes a first stage vortex knockout region to remove bulk liquids through a circular motion that imposes centrifugal forces on the gas and liquid mixture. A coalescer region located above the vortex knockout region receives the relatively lighter fluids and separates any remaining entrained liquids from the fluids. The discharge from the filtration unit is an essentially liquid free compressed gas. The liquid discharge, in the case of lube oil can be recirculated to the compressor for another cycle.
U.S. Pat. No. 7,051,540, issued May 30, 2006, to TeGrotenhuis et al., discloses a wick-containing apparatus capable of separating fluids and methods of separating fluids.
U.S. Patent Application Publication No. 20070095746, published May 3, 2007 to Minichello et al., discloses an apparatus for filtering a gas or liquid stream such as a natural gas stream. The apparatus includes a closed vessel having a longitudinally extending length, an initially open interior, an inlet port at one extent and an outlet port at an opposite extent thereof. A partition located within the vessel interior divides the vessel interior into a first chamber and a second chamber. At least one opening is provided in the partition. A filter element is disposed within the vessel to extend from within the first chamber. A special seal structure formed of a resilient material and having conically shaped sidewalls is used to seal against one end of the filter element as well as forming a dynamic seal with the vessel riser in use.
U.S. Pat. No. 7,270,690, issued Sep. 18, 2007, to Sindel, discloses a separator vane assembly made up of a number of corrugated vanes that provide serpentine paths for the gas stream therethrough. As the gas stream flows through the serpentine paths, it changes direction and liquid in the gas stream impacts the surfaces of the vanes. The upstream section of the vane assembly has roughened surfaces to decrease the surface tension of the liquid, thereby causing the liquid to coalesce. The downstream section of the vane assembly has smooth surfaces so as to increase the surface tension of the liquid. The vane assembly is followed by filters, which capture the liquid that passes through the vane assembly. The vane assembly coalesces the liquid to enable the filters to operate more effectively.
U.S. Patent Application Publication No. 20070251876, published Nov. 1, 2007 to Krogue et al., discloses an apparatus for filtering a gas or liquid stream of impurities and to filter elements used in such an apparatus. The apparatus includes a closed vessel having a longitudinally extending length, an initially open interior, an input port at one extent and an output port at an opposite extent thereof. A partition located within the vessel interior divides the vessel interior into a first stage and a second stage. At least one opening is provided in the partition. A filter element is disposed within the vessel to extend from within the first stage. The filter element is made up of a carbon block filter media surrounded by a protective porous depth filter media.
U.S. Pat. No. 7,314,508, issued Jan. 1, 2008, to Evans, discloses a desiccant cartridge having a seal therearound for forming a proper seal between the cartridge and the canister of a receiver/dryer or accumulator assembly includes a cup extending along an axis having inner wall portion and outer wall portion connected to a transverse portion to define a chamber containing desiccant particles. A cap is secured to cup to secure the desiccant particles inside the chamber. The outer wall portion is provided with the seal that is composed of a flexible thermoplastic elastomer that is resistant to heat during welding shut of the canister.
U.S. Pat. No. 7,332,010, issued Feb. 19, 2008, to Steiner, discloses a two or three phase separator including a centrifugal separator, a demister (if a three phase separator), and a filter contained within a housing. The filter uses an outside-in flow principle. The filter includes an inner layer or a center core that defines a hollow interior. An outer layer is positioned adjacent and surrounding the inner layer. The outer layer includes a re-enforcement layer, a first particle filter layer, a coalescer layer, and a second particle filter layer. An access cover of the separator includes a cover plug, an actuator cam, a plurality of idler cam plates, and a plurality of mechanisms. The access cover cooperates with an opening and an annular groove in the housing to close off and seal the separator.
U.S. Pat. No. 7,344,576, issued Mar. 18, 2008, to TeGrotenhuis et al., discloses methods of separating fluids using capillary forces and/or improved conditions. The improved methods may include control of the ratio of gas and liquid Reynolds numbers relative to the Suratman number. Also disclosed are wick-containing, laminated devices that are capable of separating fluids.
Quite commonly in pipeline applications, it is not uncommon to see multi-stage vessels, as well as a multitude of other similar filtration vessels, that utilize solid or hollow core tubular elements, typically formed at least partially a porous filtration media. Non-limiting examples of such vessels include filtration equipment such as shown in U.S. Pat. No. 5,919,284, issued Jul. 6, 1999 or U.S. Pat. No. 6,168,647, issued Jan. 2, 2001, both to Perry, Jr. et al.
U.S. Pat. No. 5,919,284 discloses a gas filter separator coalescer and multi-stage vessel for separating liquids and solids from a gas stream and simultaneously coalescing liquids from the gas stream. The apparatus includes a closed vessel having a longitudinally extending length, an initially open interior, an input port at an extent and an output port at an opposite extent thereof. There is a partition located within the vessel interior that divides the vessel interior into a first stage and a second stage. There is at least one opening in the partition. A separator/coalescer filter element is disposed within the vessel to sealingly extend from within the first stage through the opening into the second stage. There is a chevron-type seal or an O-ring seal between the filter element and the opening. The input port, vessel interior, separator/coalescer filter element and output port together define a flow passage within the apparatus, whereby the gas stream flows into the first stage through the input port and through the filter element hollow core, thereby filtering solids out of the gas stream, separating liquids from the gas stream, and pre-coalescing liquids in the gas stream. The gas stream then flows along the hollow core past the partition and back through the filter element into the second stage, thereby coalescing liquids out of the gas stream, the gas stream then exiting the second stage through the outlet port.
U.S. Pat. No. 6,168,647 discloses an apparatus for separating liquids and solids from a gas stream and simultaneously coalescing liquids from the gas stream. The apparatus includes a closed vessel having a longitudinally extending length, an initially open interior, an input port at an extent and an output port at an opposite extent thereof. There is a partition located within the vessel interior that divides the vessel interior into a first stage and a second stage. There is at least one opening in the partition. A separator/coalescer filter element is disposed within the vessel to sealingly extend from within the first stage through the opening into the second stage. There is a chevron-type seal or an O-ring seal between the filter element and the opening. The input port, vessel interior, separator/coalescer filter element and output port together define a flow passage within the apparatus, whereby the gas stream flows into the first stage through the input port and through the filter element hollow core, thereby filtering solids out of the gas stream, separating liquids from the gas stream, and pre-coalescing liquids in the gas stream. The gas stream then flows along the hollow core past the partition and back through the filter element into the second stage through a louvered impingement baffle, thereby coalescing liquids out of the gas stream, the gas stream then exiting the second stage through the outlet port. The louvered impingement baffle conditions the gas stream to create a scrubbing effect on any fine mist exiting the separator/coalescer filter element.
With such equipment as disclosed in the U.S. Pat. No. 5,919,284 or 6,168,647, it is periodically necessary to perform maintenance on the filtration vessels, including replacement of the porous filter elements. This task is labor intensive and time consuming insitu because of the mounting structure used to mount the filter elements within the filtration vessel interior. Often, it is necessary to unscrew the end cap or nut to free the filter element from its associated structural mounting within the vessel interior. Not only is this time consuming, but the location of the mounting structure is sometimes inconvenient to access, making filter replacement a difficult or inconvenient chore. The same type of inconveniences is present in the initial filter installation process for new filtration vessels.
Specifically for filter systems of the type disclosed in U.S. Pat. No. 6,168,647, there are at least two reasons for the difficulty in removing the filter elements. First, the chevron seal is working against the removal direction when trying to remove the element. Second, since the filter element extends into the riser assembly, solids collect and pack into the riser assembly. Additionally, it is not uncommon to find damage to the downstream expanded metal support grid generally caused by the elements being shoved in too far.
In an effort to overcome the problems of the prior art, especially the deficiencies of U.S. Pat. No. 5,919,284 or 6,168,647, further development was advanced in U.S. Pat. No. 7,014,685, issued Mar. 21, 2006, and U.S. Pat. No. 7,108,738, issued Sep. 19, 2006, both to Burns et al. These two patents disclose an apparatus for filtering a gas or liquid stream such as a natural gas stream. The apparatus includes a closed vessel having a longitudinally extending length, an initially open interior, an input port at one extent and an output port at an opposite extent thereof. A partition located within the vessel interior divides the vessel interior into a first stage and a second stage. At least one opening is provided in the partition. A filter element is disposed within the vessel to extend from within the first stage. The filter element is easily mounted or removed from the vessel by rotating a J-slot engagement surface on the element which mates with a post provided on a mounting structure provided on the vessel partition.
However, in spite of the above advancements that have been made in overall filtration vessel design, there still exists a need in art for apparatus and methods for filtration.
There also exists a need in the art for apparatus and methods for improvements that simplify the process of mounting and replacing filter elements within the filtration vessel, thereby decreasing the cost of vessel installation and maintenance.
As a non-limiting example of a desired improvement, for filtration systems as disclosed in U.S. Pat. Nos. 5,919,284, and 6,187,647, the portion of the filter element positioned in the downstream stage is generally a lot cleaner than the portion of the filter element positioned in the upstream stage. However, with these filtration systems, the entire filter element is removed and replaced, even though the downstream portion of the filter may be readily further used.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.